Electrical interval timer



1952 P. CAFFIER ETAL 2,522,677

ELECTRICAL INTERVAL TIMER Filed Dec. 19, 1947 }OUTPUT BY %Z, JMW

i atented Dec. 23, 1952 UNITED STATES PATENT OFFICE ELECTRICAL INTERVAL TIMER Pierre L. Caflier, Oradell, N. J., and Milton Zuckerman, Brooklyn, N. Y.

Application December 19, 1947, Serial No. 792,764

4 Claims. 1

This invention relates to a timing device designed to provide an electrical switching circuit and maintain constancy of operation under variable external conditions.

The subject matter of this invention includes apparatus making use of the warping action of a bimetallic element, when said element is heated by electrical means, to operate a detent mechanism.

More particularly this invention makes use of the time required to heat a bimetallic element to a predetermined temperature plus the time required for said element to return to a predetermined lower temperature. This total time which we will term a full pendulum cycle remains relatively constant even though the electrical heating means or the surrounding ambient temperature may vary over a comparatively wide range.

This feature is accomplished in the following manner: The bi-metallic element is heated during a relatively short period of time which we will term flash heating whereas the cooling period takes a relatively longer time. For example, in a one minute cycle the heating period may require only five seconds, whereas the cooling period will require fifty-five seconds. Since the cooling curve is a relatively constant function, the variations which may occur in the heatin period have very little effect on the total unit cycle. Variations in ambient temperature, as will be described later, are corrected by the bi-metallic structure suspension and are cancelled out.

One object of this invention is to provide an interval timing device of simple and inexpensive construction.

Another object of this invention is to provide an interval timer using a. thermo-electrical detent mechanism which will operate on direct or alternating current supply.

Another object of this invention is to provide a device of the above stated character which will operate within small tolerance of error even though the electrical power supply may vary over a relatively wide range of voltage input, say 90 to 130 volts, for example.

A further object of this invention is to provide a device of the abovestated character which will not be affected in its operation by variations in ambient temperature.

Further objects, advantages and capabilities possessed by this invention will appear in the following description and specifications:

The invention will b described with reference to the accompanying drawings, in which- Figure 1 is a diametric view showing the various elements in conjunction with electrical circuits leading thereto;

Figure 2 is a fragmentary perspective view showing a casing wall, a coil spring rearwardly thereof and connected to a shaft which carries the tooth wheel element of the device, a dial being carried by the casing for registration with a fingerpiece on the shaft and having a pointer.

Referring to the accompanying drawings for a more complete understanding of the invention, a toothed wheel is designated by numeral I, mounted on the shaft 2. Engaging alternately with the teeth of wheel I are shown arms 3 and 4, fulcrumed at points 5 and 6, said arms 3 and 4 being drawn toward the teeth of wheel I by spring I. Each arm has a beveled spur at 31c and 40:, respectively. It will be noted that when the spur of one arm lies between the teeth of toothed wheel I, the spur of the opposite arm rests on the top of the tooth, away, wheel I having been constructed with an odd number of teeth.

Fastened to pivoted block 8 is a bi-metallic element 9 so disposed that when said element warps when heated, it will strike against adjusting screws Ill and II attached to arms 3 and 4. A resistance I5, shown diagrammatically, is wound around bi-metallic element 2. At ambient temperature element 9 engages screw II to hold arm 3 out of engagement with the teeth of wheel I.

Generally designated as I2 is an electrical switch, hereinafter called the master switch, and designated as I3 is another electrical switch, hereinafter called the commutating switch.

The electrical circuit and other elements will be described in connection with the following:

In the operation of the device, a pointer I4 on shaft 2 is rotated in a clockwise direction against the force exerted by a spring I6 and brought to rest, say after five teeth of wheel I have been successively engaged by the spur of arm 4. Arm 3, of course, does not engage any teeth of wheel I as it is held away from said teeth by bimetallic element 9 now at ambient temperature.

The device is now ready for cycling: As soon as shaft 2 was rotated to set the device in operation block I! fastened to wheel I released the contacts I8, I9 of switch I2, the latter closmg to form an electrical circuit through contacts I8 and I9, via conductors 20, 2000, providing power at the point designated as output. Simultaneously, through conductors 2|, 22, and through the contacts 13m of commutator switch [3 now closed, current is allowed to flow through resistance I5.

The heat produced by current flowing through resistor l causes bimetallic element 9 to deflect at its free end to the right and exert a pressure on screw l0, forcing arm 4 to disengage from toothed wheel I. Wheel I under the action of spring It rotates counterclockwise, and arm 3 under the tension of spring I carries its spur into toothed wheel I to hold said wheel I in a new stationary position. Simultaneously, commutating switch I3 opens its contacts as its high point falls into groove Inc and breaks the electricalcircuit furnishing current to resistor 15 At this point the heating portion of the cycle is terminated and bi-metal element [5 starts to cool and deflects in the opposite direction. In so doing said bimetallic element strikes against screw H and disengages arm 3 from the groove of toothed wheel I, arm 4 latching wheel I, completing one unit cycle. The output remains unaffected.

In the stated movement of the pointer 15, the same operation is repeated five times, after the completion of which block ll opens master switch l2 and brings the device to a rest by disconnecting bimetallic element l5 and removing the electrical source of supply from the output leads.

Co-acting with element 9 is element 9a: anchored to the same block-carrier 8, the latter being pivoted at 8x, and controlled by adjusting screw 24, spring 25, and stationary block 28; The high expansion sides of both bimetallic elements will thus act in opposite directions so that any variations in ambient temperature will have no effect on the free end bimetallic element 9, as is already known in the art.

While the toothed orabutment-carrying member is shown as a wheel, it will readily be understood that it can be a movable member of other forms and that the claims are to be interpreted accordingly.

Having thus described our invention, what we claim and desire to secure by Letters Patent, is as follows:

1. In electrical interval timers, a spring-engaged toothed wheel, means including a dial and pointer for setting the position of the wheel and thereby imparting tension to the spring, a pair of spring-engaged latch arms individually pivoted, one at each side of the Wheel, an output circuit, including a switch, a master circuit breaker for said switch carried by the wheel, a second circuit including a commutator circuit-breaker actuated by said wheel-and a bi-metallic element having a resistance heater in said second circuit, said bi-metallic element being adapted at ambient temperature to hold one latch arm in neutral position, the second latch arm being spring impelled to wheel holding position, and said bimetallic element at predetermined heated position acting to efiect reverse movement of said latch arms with a dwell in action permitting a predetermined movement of the wheel sufficient for operation of the commutator circuit breaker.

2. An electrical interval timer constructed in accordance with claim 1, in combination with an adjustable member carried by each latch member for engagement :by the bi-metallic element and adapted to vary timing.

'3. In electrical interval timers, a spring-engaged toothed wheel, means including a dial and pointer for setting the position of the wheel and thereby imparting tension to the spring, a pair of spring-engaged latch arms individually pivoted, one at each side of the wheel, an output cir cuit, including a switch, a master circuit breaker for said switch carried by the wheel, a second circuit including a commutator circuit-breaker. actuated by said wheel, and a first bi-metallic element having a resistance heater in said second circuit, said first bi-metallic element being adapted at ambient temperature to hold one latch arm in neutral position, the second latch arm being spring impelled to wheel holding position, said first bi-metallic element at predetermined-heated position acting to effectreverse movement of said latch arms with a dwell in action permitting a predetermined movement or the wheel sufiicient for operation of the commutator circuit breaker, and a second bi-metallic element adapted to compensate for temperatures above the ambient temperature.

4. An electric interval timer constructed in accordance with claim 3, in combination with an adjustable member carried by each latch memher for engagement by the first bi-metallic element and adapted to vary timing, and a second lei-metallic element adapted to compensate for temperatures above the ambient temperature.

PIERRE L. CAFFIER. MILTON ZUCKERMAN.

REFERENCES CITED The following references, are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,795,013 Denman Mar. 3, 1931 2,221,863 Crane Nov. 19, 1940 2,502,180 Smulski Mar. 28, 1950 

